Ultra short wave tube



Dec. 19, 1944. I v CPP ET AL 2,365,420

ULTRA- SHORT WAVE TUBE Filed Dec. 2, 1941 Wa n foes.- Ema/N0 401 p SP W4 0 ,Z?A A 6 Patented Dec. 19, 1944 g I v 2,365,420

PATENT omce 2,365,420 utraasn oa'r WAVE runs.

Edmund LiippyErha'rd Zinlrc, and Hermann Berger, Berlin. Germany ested in the Alien Prop-- erty Custodian Application December 2, 194l$e1iial No. 421,350

In Germany October 28, 1940 4.- Claims.

Amplifying tubes for use with wave lengths less than one meter require the damping resistance to be as high as possible. It has been found that in these tubes their glass base itself materially decreases damping effects. As is well known, bases for electron tubes have been devised which are of pressed glass and admit of using inleads which are as short as possible in order to reduce the interlead capacities and inductances. For reasons of strength the customary pressed-glass bases have a wall thickness of at least 3 millimeters. In this case the damping resistance is comparatively small.

Experiments have shown the damping resistance to be considerably increased on decreasing the wall thickness. However, a comparatively small wall thickness, of less than 1 millimeter, for instance, impairs the durability of the tube base.

Furthermore, in the case of short-wave tubes the anode losses should be conducted away by radiation, since the distances between the electrodes are very small. For example, where the electrode system is a cylindrical assembly the practice has been to elongate the anode outward by fitting cooling vanes to it. However, a slight increase of the inter-electrode capacities entails that such cooling vanes act to multiply the anode losses. Further, on account of the interlead capacities and inductances the inleads should be as short'as possible, whereby the electrode system will be mounted in close proximity to the wall of the glass bulb. As a result the glass will be strongly heated by conduction and radiation.

In order to obviate these disadvantages it proposed by the present invention that in the case of pressed-glass bases for discharge ves sels the inleads be sealed into glass ribs arranged to extend radially from the middle to the ci.- cumference of the pressed-glass base and to pro- J'ect from either one or both surfaces thereof. and further, that the electrode system be mounted fiatwise with respect to this base, and finally, that the anode be provided with heat radiating means arranged merely on that side of the anode which is remote from the bottom of the base.

The heat radiating means may be a cooling vane or may be comprised of several such vanes and these may be coated with blackening material. Furthermore, the cooling vanes may be corrugated or may be fitted with intermediate ribs arranged to enlarge the surface thereof. The anode should be of suilicient wall thickness in order to insure that the heat is properly conveyed to the means serving to radiate it.

In the drawing, Fig. 1 is a diagrammatic underside view of a pressed-glass base as provided by the invention; Fig. 2 is a sectional detail of the arrangement shown in Fig. 1, Fig. 2 being drawn to a scale larger than that of Fig. 1; Figs. 3, l, 5 are diagrammatic sectional views of three embodiments of electron tubes according to the invention.

In Figs. 1 and 2, I denotes the flat or plane bottom of the pressed-glass base, 2 the cylindrical edge portion thereof, 3 indicates the glass ribs extending from the middle of base I to the edge portion 2. 4 denotes lead-in conductors or inleads sealed into some of the ribs 3, as will also appear from Fig. 2 which in addition shows the sealing bead 5 necessary for fixing the respective inlead A.

Figs. 3, 4, 5 represent the provision of heatradiating means fitted to the electrode system.

The bulb of the discharge vessel is designated 6. 1 denotes the bottom thereof. The electrode system comprises inleads 8, a cathode 9, a grid Hi, and an anode ll. 12 indicates cooling vanes fitted to the anode. In the case of Fig. 3, only one cooling vane is provided which in part extends parallel to bottom I. Figs. 4 and 5 show cooling vanes arranged to constitute a V-shaped structure. The cooling vanes represented in Figs. 3 and 4 are plane pieces of sheet metal, whereas those represented in Fig. 5 are corrugated.

The cooling vanes may be coated with blackening material to improve their radiating capacity.

The ribs 3 have a thickness of about 3 millimeters, whereas the bottom I is about 0.8 or one millimeter in thickness. A pressed-glass base so constructed has an input resistance about 15 or 20 times that of the prior devices. The ribs 3 act to strengthen the bottom 5 and thereby add to the durability of the pressed-glass base.

The novel tube base has been tested for wave lengths of 50 centimeters, 1.1 meters and 30 meters. While with a Wave length of 30 meters the difference between prior and novel construction, as regards the input resistance, was difficult to ascertain, the input resistance of the novel base was found, for a wave length of 1.1 meters, to be about 4 or 5 times the input resistance of the prior pressed-glass base. For a wave length of 50 centimeters the input resistance of the novel base proved to be of the aforesaid value, namely, 15 or 20 times the input resistance oi the prior base. With an electron tube having a pentode system mounted on the prior base the input resistance was 200 or 400 ohms, whereas in the case of a tube having that pentode system mounted on the novel base an input resistance of about 6900 or 8000 ohms was obtained.

What is claimed is:

1. An electron discharge tube for ultra hifli frequency waves of the order of one meter and less, comprising a sealed glass envelope including a very thin base having high damping re sistance at such frequencies, integral base reinforcing ribs extending radially from the periphery to the central portion of said base, an electrode system located in the envelope immediately adjacent the base, and leads to said system extending through and sealed in said ribs.

2. An electron discharge tube as set forth in claim 1, including an annular peripheral reinforcing flange extending around the base and connected to said ribs.

3. An electron discharge tube as set forth in claim 1, in which said base has a thickness of not more than about 1 millimeter.

4. An electron discharge tube as set forth in claim 1, in which the electrodes of said system extend parallel to the base and include a cylindrical anode and heat radiating extensions projecting from said anode only on the side opposite to the base, arranged to carry anode heat away from said base and toward the upper part of the envelope.

EDMUND LoPP. ERHARD ZINKE. HERMANN BERGER. 

